Hindbrain – Transverse or Axial Projection – Concepts

Ashley Davidoff MD

The Common Vein Copyright 2010

Introduction

The Pons

The Pons

The conceptual framework of the pons is overlaid on a T2 weighted MRI through the most characetristic axial image of the pons. This location is directly anterior to the widet portion of the aqueduct of Sylvius posteriorly (blue) that assumes the shape of a puffy royal crown .

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The Pons

The 4th Ventricle

TheT2 weighted MRI is a magnified view of the pons recognized commonly in the axial projection by its relationship to the 4th ventricle posteriorly which has a characteristic shape looking like a puffed up crown (blue) The pons consists of an anterior portion called the ventral pons (light pink) and the dorsal portion called the tegmentum ((darker pink). The line of distinction is vague and the dark pink line is drawn in for clarity.

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The Pontiff’s Hat that Sits on the Pons

The 4th ventricvle in the axial plane looks like the pontiff’s hat which is called the mitre A pmnemonic you may want to use to remind you of the structure that is posteriorly related to the 4th ventricle may be “The pontiff’s hat that sits on the pons”

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The Medulla

The Medulla

The medulla in the axial plane on this T 2 weighted MRI is almost rectangular in shape but is characterized by the two sets of bulges anteriorly. The medulla is divided into the anterior ventral portion portion and the posterior tegmentum. The anterior portion consists of the medial pyramidal tracts and the lateral olives .  It is these two structures that account for the symmetrically positioned anterior bulges.

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Conceptual Components of the Medulla

The medulla in the axial plane on this T 2 weighted MRI is almost rectangular in shape but is characterized by the two sets of bulges anteriorly. The medulla is divided into the anterior ventral portion portion and the posterior tegmentum. The anterior portion consists of the medial pyramidal tracts and the lateral olives

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The Medulla

4 Ice Cream Cones in a Row

The medulla at its classic location has some subtle shape diferences when compared to the midbrain and pons mostly accentuated by the olives (green)which are the second set of ice cream shaped wedges . The medial set of ice cream cones that are light pink are the medullary pyramids Posteriorly – the salmon pink bilobed section is called the tegmentum

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A Heart or a Top

The transverse Tt2 weighted MRI through the main portion of the cerebellum in the posterior cranial fossa reflects a heart shaped structure created with some artistic licence. The cerebellum consists of two cerebellar hemispheres and a central worm like vermis

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The Hemispheres and the Vermis

The T2 weighted MRI shows the 2 major components of the cerebellum – the central vermis (pink), and the two cerebellar hemispheres. The cerebellum consists of two cerebellar hemispheres and a central worm like vermis

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Winking Tabby Cat

The Winking Cat The MRI of the posterior fossa and cerebellum was rendered and reminded the author of a winking tabby cat

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